In a satellite communications system, a number of communications satellites are used to provide communications services to a number of subscriber units (SUs). Communications satellites provide the communications channels necessary for the subscriber units to obtain communication services from the system. For a satellite communications system to offer global coverage, the communications satellites are generally organized into a constellation.
The communications satellites within the constellation have specific coverage patterns on the surface of the earth. Typically, these coverage patterns comprise a number of cells. These cells are associated with beams from directional antennas located on the satellite.
In many systems, channel management is established on a cellular level. Overlap regions can occur where cells overlap, and cell overlap, among other things, can lead to interference problems.
Cells usually have a limited amount of capacity associated with them. In some systems, the amount of capacity is determined by the amount of channels that are allowed to occur within a cell. Maximizing the utilization of this limited channel capacity is paramount in providing communications services to a large number of subscribers.
Maximizing spectral efficiency in a satellite communications system means consuming only those channels needed to service the instantaneous demand. An ideal system would allocate channels to subscribers in real time as demand for the channels is presented to the system. An ideal system would also allocate channels on a non-interfering basis.
What are needed are a method and apparatus for examining in real time an interference potential for each channel based on a subscriber unit's location relative to a set of active channels and for allocating a channel based on minimizing an interference potential.